JP6536687B2 - Capacity maintenance rate estimation device or capacity maintenance rate estimation method - Google Patents

Capacity maintenance rate estimation device or capacity maintenance rate estimation method Download PDF

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JP6536687B2
JP6536687B2 JP2017551494A JP2017551494A JP6536687B2 JP 6536687 B2 JP6536687 B2 JP 6536687B2 JP 2017551494 A JP2017551494 A JP 2017551494A JP 2017551494 A JP2017551494 A JP 2017551494A JP 6536687 B2 JP6536687 B2 JP 6536687B2
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浩明 橋本
浩明 橋本
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Nissan Motor Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G01R31/3842—Arrangements for monitoring battery or accumulator variables, e.g. SoC combining voltage and current measurements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/3644—Constructional arrangements
    • G01R31/3648—Constructional arrangements comprising digital calculation means, e.g. for performing an algorithm
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G01R31/387—Determining ampere-hour charge capacity or SoC
    • G01R31/388—Determining ampere-hour charge capacity or SoC involving voltage measurements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/392—Determining battery ageing or deterioration, e.g. state of health
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • General Physics & Mathematics (AREA)
  • Secondary Cells (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
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Description

本発明は、バッテリの容量維持率推定装置又はバッテリの容量維持率推定方法に関するものである。   The present invention relates to a battery capacity maintenance rate estimation device or a battery capacity maintenance rate estimation method.

電池容量を算出できる電池容量算出方法が知られている。この電池容量算出方法は、バッテリの充電期間内における所定電流積算期間のセンサ電流の積算値に基づいて電流積算充電率変化量を算出し、バッテリの状態量に基づいて所定電流積算期間の開始時および終了時の開放電圧を推定し、推定した開放電圧から所定電流積算期間の開始時および終了時の充電率を求め、両者の差分から開放電圧充電率変化量を算出する。そして、開放電圧充電率変化量に対する電流積算充電率変化量の比である容量維持率を算出し、バッテリの初期バッテリ容量に容量維持率を乗算してバッテリの電池容量を算出する（特許文献１）。   A battery capacity calculation method capable of calculating the battery capacity is known. This battery capacity calculation method calculates the current integrated charging rate change amount based on the integrated value of the sensor current in the predetermined current integration period within the charging period of the battery, and at the start of the predetermined current integration period based on the state amount of the battery The open circuit voltage at the end is estimated, the charging rate at the start and end of the predetermined current integration period is determined from the estimated open circuit voltage, and the open circuit charging rate change amount is calculated from the difference between the two. Then, the capacity retention rate, which is the ratio of the current integrated charge rate change amount to the open voltage charge rate change amount, is calculated, and the initial battery capacity of the battery is multiplied by the capacity retention rate to calculate the battery capacity of the battery (Patent Document 1) ).

特開２０１１−２１５１２５号公報JP 2011-215125 A

しかしながら、センサの検出誤差によって、容量維持率の演算精度が低いという問題があった。   However, there has been a problem that the calculation accuracy of the capacity retention rate is low due to the detection error of the sensor.

本発明が解決しようとする課題は、容量維持率の推定精度の高い容量維持率推定装置及び容量維持率推定方法を提供することである。   Problem to be solved by the invention is providing the capacity | capacitance maintenance factor estimation apparatus and the capacity | capacitance maintenance factor estimation method with high estimation accuracy of a capacity | capacitance maintenance factor.

本発明は、バッテリの電流の絶対値が０アンペア近傍になる第１時点からバッテリの電流の絶対値が０アンペア近傍になる第２時点までの期間を積算期間として特定し、積算期間におけるバッテリの電流の積算値を演算し、バッテリの検出電圧に基づき当該第１時点における第１開放電圧及び当該第２時点における第２開放電圧を演算し、当該第１開放電圧と当該第２開放電圧との電圧差と所定の条件を満たす積算値とに基づきバッテリの容量維持率を推定し、積算値が所定の下限値以上であり、かつ、前記積算期間における前記バッテリの電流の平均値が所定値以上であることを当該所定の条件とすることによって上記課題を解決する。   The present invention specifies a period from a first point in time when the absolute value of the battery current is near 0 amperes to a second point in time when the absolute value of the battery current is near 0 amperes as the integration period. The integrated value of the current is calculated, and the first open voltage at the first time and the second open voltage at the second time are calculated based on the detection voltage of the battery, and the first open voltage and the second open voltage are calculated. The capacity retention rate of the battery is estimated based on the voltage difference and the integrated value satisfying a predetermined condition, the integrated value is equal to or higher than a predetermined lower limit, and the average value of the current of the battery in the integration period is equal to or higher than a predetermined value. The above-mentioned subject is solved by making it that the predetermined conditions.

本発明によれば、センサの検出誤差に対して影響の小さい電流積算値を用いて、容量維持率を演算するため、容量維持率の推定精度を高めることができる、という効果を奏する。   According to the present invention, since the capacity retention rate is calculated using the current integration value that has a small influence on the detection error of the sensor, the estimation accuracy of the capacity retention rate can be enhanced.

本実施形態に係る容量維持率推定装置を備えたバッテリパックのブロック図である。It is a block diagram of a battery pack provided with a capacity maintenance rate estimating device concerning this embodiment. 図１のバッテリコントローラのブロック図である。It is a block diagram of the battery controller of FIG. 図１のバッテリコントローラの制御フローを示すフローチャートである。It is a flowchart which shows the control flow of the battery controller of FIG. バッテリの電流積算値に対するＯＣＶ変化量の特性を示すグラフである。It is a graph which shows the characteristic of the amount of OCV change to the current integration value of a battery. 図１の電流センサの検出電流に対する誤差の変化を示すグラフである。It is a graph which shows the change of the difference | error with respect to the detection current of the current sensor of FIG. 図１のバッテリの電流の経時的な変化を示すグラフである。It is a graph which shows the time-dependent change of the electric current of the battery of FIG. 図１のバッテリの分極による電流変化を示すグラフであって、（ａ）は電流変化を示すグラフであり、（ｂ）は電圧変化を示すグラフである。It is a graph which shows the electric current change by polarization of the battery of FIG. 1, Comprising: (a) is a graph which shows an electric current change, (b) is a graph which shows a voltage change. 図１のバッテリの電流積算値と容量維持率の演算誤差との関係を示すグラフである。It is a graph which shows the relationship between the electric current integral value of the battery of FIG. 1, and the calculation error of a capacity | capacitance maintenance factor. 図１のバッテリのＳＯＣ演算値の誤差変化を示すグラフである。It is a graph which shows the error change of the SOC calculated value of the battery of FIG. 図１のバッテリの状態変化（充電時）を示すグラフであって、（ａ）は電流変化を示すグラフであり、（ｂ）はＳＯＣ変化を示すグラフである。It is a graph which shows the state change (at the time of charge) of the battery of FIG. 1, Comprising: (a) is a graph which shows electric current change, (b) is a graph which shows SOC change. 図１のバッテリの状態変化（充電時）を示すグラフであって、（ａ）は電流変化を示すグラフであり、（ｂ）は電圧変化を示すグラフである。It is a graph which shows the state change (at the time of charge) of the battery of FIG. 1, Comprising: (a) is a graph which shows electric current change, (b) is a graph which shows voltage change. 図１のバッテリの状態変化（放電時）を示すグラフであって、（ａ）は電流変化を示すグラフであり、（ｂ）はＳＯＣ変化を示すグラフである。It is a graph which shows the state change (at the time of discharge) of the battery of FIG. 1, Comprising: (a) is a graph which shows electric current change, (b) is a graph which shows SOC change. 図１のバッテリの温度に対する内部抵抗の変化を示すグラフである。It is a graph which shows the change of the internal resistance with respect to the temperature of the battery of FIG.

以下、本発明の実施形態を図面に基づいて説明する。
《第１実施形態》Hereinafter, embodiments of the present invention will be described based on the drawings.
First Embodiment

図１は、本実施形態に係る容量維持率推定装置を備えたバッテリパックのブロック図である。容量維持率推定装置は、バッテリの容量維持率（劣化度に相当）を推定するための装置である。本実施形態では、容量維持率推定装置はバッテリパック内に搭載されている。容量維持率推定装置は、必ずしもバッテリパック内に搭載されている必要なく、バッテリパックの外部に設けられていてもよい。   FIG. 1 is a block diagram of a battery pack provided with a capacity maintenance rate estimation device according to the present embodiment. The capacity maintenance rate estimation device is a device for estimating the capacity maintenance rate (corresponding to the degree of deterioration) of the battery. In the present embodiment, the capacity maintenance ratio estimation device is mounted in the battery pack. The capacity maintenance ratio estimation device does not necessarily have to be mounted in the battery pack, and may be provided outside the battery pack.

バッテリパック１は、セル１０及びバッテリコントローラ２０を備えている。バッテリパック１は、二次電池及びコントローラをモジュール化したデバイスである。バッテリパック１は、車両用の電源又は定置用の電源等に用いられる。   The battery pack 1 includes a cell 10 and a battery controller 20. The battery pack 1 is a device in which a secondary battery and a controller are modularized. The battery pack 1 is used as a power supply for vehicles or a power supply for stationary.

セル１０は、バッテリ１１、電流センサ１２、電圧センサ１３、及び温度センサ１４を有している。バッテリ１１は、複数の二次電池を直列又は並列に接続した組電池である。バッテリ１１は、バッテリパック１に接続された負荷に対して、電力を出力する。バッテリ１１は、バッテリパック１に接続された充電器により充電可能である。バッテリ１１は、負荷の回生により充電されてもよい。二次電池は、リチウムイオン電池等である。   The cell 10 includes a battery 11, a current sensor 12, a voltage sensor 13, and a temperature sensor 14. The battery 11 is an assembled battery in which a plurality of secondary batteries are connected in series or in parallel. The battery 11 outputs power to the load connected to the battery pack 1. The battery 11 can be charged by a charger connected to the battery pack 1. The battery 11 may be charged by regeneration of the load. The secondary battery is a lithium ion battery or the like.

電流センサ１２は、バッテリ１１の充電電流及び放電電流を検出する。電圧センサ１３はバッテリ１１の電圧を検出する。温度センサ１４は、バッテリ１１の付近に設置されており、バッテリ１１の温度を検出する。電流センサ１２、電圧センサ１３及び温度センサ１４の検出値はバッテリコントローラ２０に出力される。   The current sensor 12 detects the charge current and the discharge current of the battery 11. The voltage sensor 13 detects the voltage of the battery 11. The temperature sensor 14 is installed near the battery 11 and detects the temperature of the battery 11. Detection values of the current sensor 12, the voltage sensor 13 and the temperature sensor 14 are output to the battery controller 20.

バッテリコントローラ２０は、電流センサ１２、電圧センサ１３、及び温度センサ１４の検出値に基づき、バッテリ１１の状態を管理する。   The battery controller 20 manages the state of the battery 11 based on the detection values of the current sensor 12, the voltage sensor 13, and the temperature sensor 14.

次に、図２を用いて、バッテリコントローラ２０の構成について説明する。図２はバッテリコントローラ２０のブロック図である。バッテリコントローラ２０は、ＣＰＵ、ＲＯＭ、ＲＡＭ等を備えている。バッテリコントローラ２０は、バッテリ１１の状態の管理機能を動作するための機能ブロックとして、ゼロ電流時点特定部２１、電流積算値演算部２２、平均電流演算部２３、推定条件判定部２４、ΔＳＯＣ−ｉ演算部２５、ＯＣＶ演算部２６、ΔＳＯＣ−ｖ演算部２７、容量維持率演算部２８、及び満充電容量演算部２９を有している。   Next, the configuration of the battery controller 20 will be described with reference to FIG. FIG. 2 is a block diagram of the battery controller 20. As shown in FIG. The battery controller 20 includes a CPU, a ROM, a RAM, and the like. The battery controller 20 is a functional block for operating the management function of the state of the battery 11; the zero current time specifying unit 21, the current integrated value calculating unit 22, the average current calculating unit 23, the estimation condition determining unit 24, ΔSOC-i The calculation unit 25, the OCV calculation unit 26, the ΔSOC-v calculation unit 27, the capacity retention ratio calculation unit 28, and the full charge capacity calculation unit 29 are included.

ゼロ電流時点特定部２１は、電流センサ１２の検出電流に基づき、バッテリの電流の絶対値が０アンペア近傍である時点を、ゼロ電流時点として特定する。０アンペア近傍は、０以上所定値未満の範囲を示している。所定値は、バッテリ１１の充放電電流がゼロであると判断できる値、言い換えるとバッテリ１１に負荷がかかっていない（充放電していない）と判断できる値である。所定値は、電流センサ１２の誤差又はバッテリ１１の性質等により予め設定されている。バッテリ１１の放電電流又は充電電流は、バッテリ１１の使われ方に応じて時系列で変化する。そのため、ゼロ電流時点は、時系列に特定される。   Based on the detection current of the current sensor 12, the zero current point specification unit 21 specifies a point at which the absolute value of the current of the battery is near 0 amperes as a zero current point. The vicinity of 0 amps indicates a range of 0 or more and less than a predetermined value. The predetermined value is a value that can determine that the charge and discharge current of the battery 11 is zero, in other words, a value that can determine that the battery 11 is not loaded (not charged and discharged). The predetermined value is preset according to the error of the current sensor 12 or the property of the battery 11 or the like. The discharge current or charge current of the battery 11 changes in time series depending on how the battery 11 is used. Therefore, the zero current point is specified in time series.

電流積算値演算部２２は、複数のゼロ電流時点の間の時間を積算時間として特定しつつ、電流センサ１２の検出電流を積算することで、当該積算期間におけるバッテリ電流の積算値を演算する。   The current integration value calculation unit 22 calculates the integration value of the battery current in the integration period by integrating the detection current of the current sensor 12 while specifying the time between the plurality of zero current points as the integration time.

平均電流演算部２３は、電流センサ１２の検出電流に基づき、積算期間におけるバッテリ１１の平均電流を演算する。   The average current calculation unit 23 calculates the average current of the battery 11 in the integration period based on the detected current of the current sensor 12.

推定条件判定部２４は、積算期間における電流積算値が、推定条件を満たしているか否かを判定する。推定条件は、電流積算値が容量維持率の推定のために適した値であることを示した条件である。推定条件は、積算期間における電流積算値が所定の下限値以上であり、かつ、積算期間における平均電流が平均電流閾値以上であることである。電流積算値の下限値及び平均電流閾値は、電流センサ１２の誤差範囲に応じて予め設定されている。推定条件を満たしていない電流積算値は、容量維持率の推定に適した値ではないため、演算対象から除外される。   The estimation condition determination unit 24 determines whether the current integration value in the integration period satisfies the estimation condition. The estimation condition is a condition indicating that the current integration value is a value suitable for estimation of the capacity maintenance rate. The estimation condition is that the current integrated value in the integration period is equal to or higher than a predetermined lower limit, and the average current in the integration period is equal to or higher than the average current threshold. The lower limit value of the current integrated value and the average current threshold value are preset according to the error range of the current sensor 12. The current integrated value which does not satisfy the estimation condition is not a value suitable for estimation of the capacity maintenance rate, and is therefore excluded from the calculation target.

ΔＳＯＣ−ｉ演算部２５は、推定条件を満たす電流積算値に対応するＳＯＣの差を演算する。すなわちΔＳＯＣ−ｉ演算部２５は、積算期間の始点から終点までの電流積算量（Ａｈ）をバッテリの新品時における満充電容量（Ａｈ）で除算する事によって、積算期間の始点から終点までの間のＳＯＣの変化量を算出する。ＯＣＶ演算部２６は、電圧センサ１３の検出電圧に基づき、ゼロ電流時点における開放電圧を演算する。積算期間の始点と終点は、ゼロ電流時点となる。そのため、ＯＣＶ演算部２６は、温度や劣化度によって変化するバッテリ１１の内部抵抗の影響を極力抑制して、積算期間の始点と終点それぞれについて、開放電圧を演算することができる。なお、以下では開放電圧をＯＣＶ（Ｏｐｅｎ Ｃｉｒｃｕｉｔ Ｖｏｌｔａｇｅ）とも記載する。   The ΔSOC-i calculation unit 25 calculates the difference of the SOC corresponding to the current integration value that satisfies the estimation condition. That is, the ΔSOC-i calculation unit 25 divides the integrated current amount (Ah) from the start point to the end point of the integration period by the full charge capacity (Ah) at the time of the new battery, Calculate the amount of change in SOC. The OCV calculator 26 calculates an open circuit voltage at a zero current point based on the detection voltage of the voltage sensor 13. The start point and the end point of the integration period are zero current points. Therefore, the OCV calculating unit 26 can calculate the open circuit voltage for each of the start point and the end point of the integration period, while minimizing the influence of the internal resistance of the battery 11 which changes depending on the temperature and the degree of deterioration. In the following, the open circuit voltage is also referred to as OCV (Open Circuit Voltage).

ΔＳＯＣ−ｖ演算部２７は、積算期間の始点における開放電圧と、積算期間の終点における開放電圧との電圧差を演算する。ΔＳＯＣ−ｖ演算部２７は、演算した電圧差に対応するＳＯＣの差を演算する。すなわちΔＳＯＣ−ｖ演算部２７は、積算期間の始点における開放電圧と終点における開放電圧との差に基づいて、積算期間の始点から終点までの間のＳＯＣの変化量を算出する。   The ΔSOC-v calculator 27 calculates a voltage difference between the open circuit voltage at the start of the integration period and the open circuit voltage at the end of the integration period. The ΔSOC-v computing unit 27 computes the difference of SOC corresponding to the computed voltage difference. That is, based on the difference between the open circuit voltage at the start point of the integration period and the open circuit voltage at the end point, the ΔSOC-v calculation unit 27 calculates the amount of change in SOC from the start point to the end point of the integration period.

容量維持率演算部２８は、ΔＳＯＣ−ｉ演算部２５により演算されたＳＯＣ差（ΔＳＯＣ−ｉ）とΔＳＯＣ−ｖ演算部２７により演算されたＳＯＣ差（ΔＳＯＣ−ｖ）に基づき、バッテリ１１の現在の容量維持率を演算する。容量維持率演算部２８は、ΔＳＯＣ−ｉ演算部２５により演算されたＳＯＣ差（ΔＳＯＣ−ｉ）をΔＳＯＣ−ｖ演算部２７により演算されたＳＯＣ差（ΔＳＯＣ−ｖ）で割ることで、現在の容量維持率を演算する。すなわち、ΔＳＯＣ−ｉ演算部２５による演算、ΔＳＯＣ−ｖ演算部２７による演算、及び、容量維持率演算部２８による演算により、容量維持率が推定される。そして、満充電容量演算部２９は、現在の容量維持率及びバッテリ１１の初期の満充電容量に基づき、バッテリ１１の現在の満充電容量を演算する。   Based on the SOC difference (ΔSOC-i) calculated by the ΔSOC-i calculation unit 25 and the SOC difference (ΔSOC-v) calculated by the ΔSOC-v calculation unit 27, the capacity maintenance ratio calculation unit 28 Calculate the capacity retention rate of The capacity maintenance ratio calculation unit 28 divides the SOC difference (ΔSOC-i) calculated by the ΔSOC-i calculation unit 25 by the SOC difference (ΔSOC-v) calculated by the ΔSOC-v calculation unit 27 to obtain the current value. Calculate the capacity retention rate. That is, the capacity maintenance ratio is estimated by the calculation by the ΔSOC-i calculation unit 25, the calculation by the ΔSOC-v calculation unit 27, and the calculation by the capacity maintenance ratio calculation unit. Then, the full charge capacity calculation unit 29 calculates the current full charge capacity of the battery 11 based on the current capacity maintenance rate and the initial full charge capacity of the battery 11.

次に、バッテリコントローラ２０が満充電容量を演算する際の制御フローを、図３を用いて、図３は、バッテリコントローラ２０の制御フローを示すフローチャートである。なお、図３に示す制御フローは、ゼロ電流時点を特定したタイミングで繰り返し実行される。   Next, a control flow when the battery controller 20 calculates the full charge capacity will be described using FIG. 3 and FIG. 3 is a flowchart showing a control flow of the battery controller 20. The control flow shown in FIG. 3 is repeatedly executed at the timing at which the zero current point is specified.

ステップＳ１にて、電流積算値演算部２２は、前回のゼロ電流時点から今回のゼロ電流時点までの電流積算値を演算する。   In step S1, the current integrated value calculator 22 calculates a current integrated value from the previous zero current point to the current zero current point.

ステップＳ２にて、平均電流演算部２３は、前回のゼロ電流時点から今回のゼロ電流時点までの平均電流を演算する。   In step S2, the average current calculator 23 calculates the average current from the previous zero current point to the current zero current point.

ステップＳ３にて、推定条件判定部２４は、電流積算値が予め定めた下限値以上から上限値以下までの範囲内であるか否かを判定する。電流積算値が下限値未満である場合、又は、電流積算値が上限値より大きい場合には、制御フローを終了する。電流積算値が下限値以上から上限値以下までの範囲内である場合には、制御フローはステップＳ４に進む。   In step S3, the estimation condition determination unit 24 determines whether or not the current integrated value is in the range from the predetermined lower limit value to the upper limit value. If the current integrated value is less than the lower limit value or if the current integrated value is greater than the upper limit value, the control flow is ended. If the current integrated value is within the range from the lower limit value to the upper limit value, the control flow proceeds to step S4.

ステップＳ４にて、推定条件判定部２４は、平均電流値が予め定めた平均電流閾値以上であるか否かを判定する。平均電流値が平均電流閾値未満である場合には、制御フローを終了する。平均電流値が平均電流閾値以上である場合には、制御フローはステップＳ５に進む。   In step S4, the estimation condition determination unit 24 determines whether the average current value is equal to or greater than a predetermined average current threshold. If the average current value is less than the average current threshold, the control flow is ended. If the average current value is equal to or higher than the average current threshold, the control flow proceeds to step S5.

ここで、ステップＳ３，４の制御フローの判定に用いた推定条件について、説明する。まず、推定条件のうち電流積算値の下限値について図４を用いて説明する。図４は、電流積算値と開放電圧の変化量との関係を示すグラフである。グラフａはバッテリ１１の新品時の特性を示す。グラフｂは、バッテリ１１の満充電容量が半分になった時の特性を示す。バッテリ１１の電流積算値と、電流積算値に相当するＯＣＶの変化量をそれぞれ測定すると、測定値は図４に示すような点でプロットされる。電流積算値とＯＣＶ変化量との間には比例関係がある。ただし、バッテリの劣化が進むと、満充電容量の低下に応じて電流積算値に対するＯＣＶ変化量が大きくなり、グラフの傾きが大きくなる。   Here, the estimation conditions used for determination of the control flow of step S3, 4 are demonstrated. First, among the estimation conditions, the lower limit value of the current integration value will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the integrated current value and the amount of change in open circuit voltage. The graph a shows the characteristics when the battery 11 is new. The graph b shows the characteristic when the full charge capacity of the battery 11 is halved. When the current integrated value of the battery 11 and the variation of the OCV corresponding to the current integrated value are respectively measured, the measured values are plotted at points as shown in FIG. There is a proportional relationship between the current integration value and the OCV change amount. However, as the deterioration of the battery progresses, the OCV change amount with respect to the current integrated value increases as the full charge capacity decreases, and the slope of the graph increases.

ここで、電流積算値はバッテリ１１の残充電電荷量の変化量に相当する。一方、ＯＣＶはＳＯＣ（Ｓｔａｔｅ Ｏｆ Ｃｈａｒｇｅ:満充電時の充電電荷量に対する残充電電荷量の割合）と相関が有り、従って、ＯＣＶの変化量はバッテリ１１のＳＯＣの変化量に相当する。このため、残充電電荷量の変化量に相当する電流積算値とＳＯＣに相当するＯＣＶの変化量とは相関する。但し、残充電電荷量の変化量である電流積算値が同じであっても、バッテリの劣化による満充電時の充電電荷量（満充電容量）の低下に伴ってＳＯＣの変化量に相当するＯＣＶの変化量は大きくなる。なお、上述の通りＯＣＶはＳＯＣと相関が有り、ＳＯＣはＯＣＶから一義的に導き出せるため、 実質的にはＯＣＶとＳＯＣとは同義である。   Here, the current integrated value corresponds to the amount of change of the remaining charge amount of the battery 11. On the other hand, OCV has a correlation with SOC (State Of Charge: a ratio of the remaining charge amount to the charge amount at the time of full charge). Therefore, the change amount of OCV corresponds to the change amount of the SOC of the battery 11. Therefore, the current integrated value corresponding to the change amount of the remaining charge amount and the change amount of the OCV corresponding to the SOC are correlated. However, even if the integrated value of current, which is the amount of change in the amount of remaining charge, is the same, the OCV corresponds to the amount of change in SOC with the decrease in the amount of charge (full charge capacity) at full charge due to battery deterioration. The amount of change in As described above, OCV has a correlation with SOC, and since SOC can be uniquely derived from OCV, OCV and SOC are substantially the same.

図４のグラフにより、電流積算値が小さい時には、ＯＣＶ変化量が小さい。そして、電流積算値が小さい時には、ＯＣＶの変化量が小さい分、ＯＣＶの変化量に対して、電流センサ１２の誤差の影響が大きくなる。すなわち、電流積算値が小さい時には、ＯＣＶの変化が、バッテリ１１の充放電による変化か、電流センサの誤差による変化なのか、判別が難しい。そのため、本実施形態では、推定条件として電流積算値の下限値が設定されている。   According to the graph of FIG. 4, when the current integrated value is small, the OCV change amount is small. When the current integrated value is small, the amount of change in the OCV is small, and the influence of the error of the current sensor 12 on the amount of change in the OCV becomes large. That is, when the current integrated value is small, it is difficult to determine whether the change in the OCV is a change due to charge and discharge of the battery 11 or a change due to an error of the current sensor. Therefore, in the present embodiment, the lower limit value of the current integration value is set as the estimation condition.

次に、推定条件のうち電流積算値の上限値について図５を用いて説明する。図５は、電流センサの検出値と誤差との関係を示すグラフである。   Next, among the estimation conditions, the upper limit value of the current integration value will be described using FIG. FIG. 5 is a graph showing the relationship between the detection value of the current sensor and the error.

図５に示すように、電流センサ１２の誤差特性は、電流ゼロの時の誤差を最小値とした２次曲線となる。すなわち、電流値の絶対値が大きくなるほど、誤差は大きくなる。電流積算値が大きくなると、電流センサの誤差が積み上がることになり、電流積算値に対する誤差の影響が大きくなる。そのため、本実施形態では、推定条件として電流積算値の上限値が設定されている。
上述の通り、電流積算値が下限値より小さい場合には、ＯＣＶの変化量に対して、電流センサ１２の誤差の影響が大きくなる。一方で、電流値が大きく、電流積算値が上限値より大きい場合には、電流センサの誤差による電流積算値に対する誤差の影響が大きくなる。このため、電流積算値の上限値及び下限値は、電流センサの誤差による影響を抑制できるような値を、予め実験等によって定めたものである。As shown in FIG. 5, the error characteristic of the current sensor 12 is a quadratic curve in which the error at the time of current zero is a minimum value. That is, the larger the absolute value of the current value, the larger the error. As the current integration value increases, the error of the current sensor is accumulated, and the influence of the error on the current integration value becomes large. Therefore, in the present embodiment, the upper limit value of the current integration value is set as the estimation condition.
As described above, when the current integrated value is smaller than the lower limit value, the influence of the error of the current sensor 12 on the amount of change of the OCV becomes large. On the other hand, when the current value is large and the current integration value is larger than the upper limit value, the influence of the error on the current integration value due to the error of the current sensor becomes large. For this reason, the upper limit value and the lower limit value of the current integration value are values determined in advance by experiments etc. so as to suppress the influence of the error of the current sensor.

推定条件のうち平均電流閾値について図５を用いて説明する。バッテリ１１の容量維持率の演算式は、開放電圧に基づくＳＯＣ差（ΔＳＯＣ−ｖ）を分子とし、電流積算値に基づくＳＯＣ差（ΔＳＯＣ−i ）を分母としている。図５に示す特性より、バッテリ１１の電流（充放電電流）が小さい場合には、検出電流値の誤差は小さくなる。容量維持率の演算式において、検出電流値の誤差成分は分母に影響する。そのため、検出電流値の誤差が小さいほど容量維持率の演算値に対する影響が小さくなる。そこで、本実施形態では、推定条件として平均電流閾値が設定されている。   Among the estimation conditions, the average current threshold will be described with reference to FIG. The equation for calculating the capacity retention rate of the battery 11 uses the SOC difference (ΔSOC-v) based on the open circuit voltage as a numerator and the SOC difference (ΔSOC-i) based on the current integration value as a denominator. From the characteristics shown in FIG. 5, when the current (charge / discharge current) of the battery 11 is small, the error of the detected current value becomes small. The error component of the detected current value affects the denominator in the equation for calculating the capacity retention rate. Therefore, the smaller the error of the detected current value, the smaller the influence on the calculated value of the capacity retention rate. Therefore, in the present embodiment, an average current threshold is set as the estimation condition.

また、平均電流閾値を設定する他の理由として、以下の理由が挙げられる。例えば一例として、電流の経時的変化が図６に示すような変化であると仮定する。図６は、電流の経時的変化を示すグラフである。図６に示すような電流変化において、電流積算値は下限値以上から上限値以下までの範囲内とする。   Also, as another reason for setting the average current threshold, the following reasons can be mentioned. For example, it is assumed that the change with time of the current is a change as shown in FIG. 6 as an example. FIG. 6 is a graph showing temporal changes in current. In the current change as shown in FIG. 6, the current integration value is in the range from the lower limit value to the upper limit value.

図６に示す電流変化では、時間ｔ１までの高電流の期間は短く、時間ｔ１以降の低電流の期間は長くなっている。時間ｔ１以降、電流値は低いため、電流センサ１２の誤差は小さい。しかしながら、時間ｔ１以降の低電流の期間が長いため、小さな電流誤差が長い時間をかけて積み上がることになり、その結果、電流積算値に含まれる全体の誤差は大きくなる。そのため、本実施形態では、推定条件として平均電流閾値が設定されている。図６に示すような電流変化では、平均電流が平均電流閾値未満となるため、推定条件を満たさないことになる。In the current change shown in FIG. 6, a period of high current up to the time t 1 is short, the period of time t 1 after the low current is longer. Time t 1 later, since the current value is low, the error of the current sensor 12 is small. However, since the low current period after time t 1 is long, a small current error is accumulated over a long time, and as a result, the overall error included in the current integration value becomes large. Therefore, in the present embodiment, an average current threshold is set as the estimation condition. In the current change as shown in FIG. 6, since the average current is smaller than the average current threshold, the estimation condition is not satisfied.

ステップＳ３及びステップＳ４の制御フローにおいて、推定条件を満たす場合には、ＯＣＶ演算部２６は、前回のゼロ電流時点における開放電圧（ＯＣＶ１）と今回のゼロ電流時点における開放電圧（ＯＣＶ２）を演算する。In the control flow of step S3 and step S4, when the estimation condition is satisfied, the OCV calculation unit 26 compares the open circuit voltage (OCV 1 ) at the previous zero current time point and the open circuit voltage (OCV 2 ) at the current zero current time point. Calculate

図７を用いて、開放電圧の演算に用いられる検出電圧の検出タイミングについて説明する。図７は、ゼロ電流時点（ｔａ）の前後におけるバッテリ１１電流変化（図７（ａ）に示す電流変化）及び電圧変化（図７（ｂ）に示す電圧変化）を示すグラフである。The detection timing of the detection voltage used for the calculation of the open circuit voltage will be described with reference to FIG. Figure 7 is a graph showing the battery 11 current changes (Fig. 7 (current change is shown in a)) and the voltage change (voltage change shown in FIG. 7 (b)) before and after the zero current point (t a).

図７に示すように、バッテリ１１の充電電流は、時間ｔａでゼロになる。バッテリ１１の電圧は、時間ｔａで下がり始めるが、分極現象によって、時間ｔａでは完全には下がらない。バッテリ１１の電圧は、時間ｔａ以降も徐々に下がる。そして、時間ｔｂで、分極がほぼ解消され、バッテリ１１の電圧は下がりきった電圧となる。すなわち、時間ｔａから時間ｔｂまでの間は分極期間となり、バッテリ電圧が不安定な状態なる。そして、分極期間中の検出電圧に基づいて、開放電圧が演算された場合には、演算誤差の要因にもなる。そのため、ＯＣＶ演算部２６は、ゼロ電流時点から所定の分極期間の経過後の検出電圧に基づき開放電圧を演算している。分極期間は、バッテリ１１の特性に応じて予め設定されている。また、ＯＣＶ演算部２６は、バッテリの電圧の大きさに応じて、分極時間の長さを設定してよい。これにより、分極が解消された電圧に基づき開放電圧を演算しているため、開放電圧の演算精度を高めることができる。As shown in FIG. 7, the charging current of the battery 11 becomes zero at time t a. The voltage of the battery 11 starts to fall at time t a but does not fall completely at time t a due to the polarization phenomenon. The voltage of the battery 11 also gradually decreases after time t a . Then, at time t b , the polarization is almost eliminated, and the voltage of the battery 11 becomes a completely lowered voltage. That is, during the time t a to time t b becomes polarized period, the battery voltage is unstable. When the open circuit voltage is calculated based on the detected voltage during the polarization period, it also becomes a factor of the calculation error. Therefore, the OCV computing unit 26 computes the open circuit voltage based on the detected voltage after the lapse of the predetermined polarization period from the zero current time point. The polarization period is preset according to the characteristics of the battery 11. Further, the OCV calculating unit 26 may set the length of the polarization time in accordance with the magnitude of the voltage of the battery. Thus, since the open circuit voltage is calculated based on the voltage in which the polarization is eliminated, the calculation accuracy of the open circuit voltage can be enhanced.

ステップＳ５の制御フローにて開放電圧（ＯＣＶ１、ＯＣＶ２）を演算した後、ステップＳ６にて、ΔＳＯＣ−ｖ演算部２７は、今回の開放電圧（ＯＣＶ２）に対応する充電状態（ＳＯＣ：Ｓｔａｔｅ ｏｆ Ｃｈａｒｇｅ）を演算する。開放電圧とＳＯＣとの間には相関関係がある。ΔＳＯＣ−ｖ演算部２７は、この相関関係をマップとして予め記憶し、当該マップを参照してＳＯＣを演算する。そして、ΔＳＯＣ−ｖ演算部２７は、今回の開放電圧（ＯＣＶ２）に対応するＳＯＣ２と前回の開放電圧（ＯＣＶ１）に対応するＳＯＣ１との差分を演算することで、ＳＯＣの変化量（ΔＳＯＣ−ｖ）を演算する。After the open voltage (OCV 1 , OCV 2 ) is calculated in the control flow of step S5, in step S6, the ΔSOC-v calculation unit 27 calculates the state of charge (SOC :) corresponding to the current open voltage (OCV 2 ). Calculate State of Charge). There is a correlation between the open circuit voltage and the SOC. The ΔSOC-v computing unit 27 prestores the correlation as a map, and computes the SOC with reference to the map. Then, the ΔSOC-v calculation unit 27 calculates the difference between the SOC 2 corresponding to the current open voltage (OCV 2 ) and the SOC 1 corresponding to the previous open voltage (OCV 1 ), thereby changing the SOC change amount. Calculate (ΔSOC−v).

ステップＳ７にて、ΔＳＯＣ−ｉ演算部２５は、現在のバッテリ１１の満充電容量に対する電流積算値の比で表す演算式によって、ＳＯＣ変化量（ΔＳＯＣ−ｉ）を演算する。ステップＳ８にて、容量維持率演算部２８は、ＳＯＣ変化量（ΔＳＯＣ−ｉ）に対するＳＯＣ変化量（ΔＳＯＣ−ｖ）の比で表す演算式によって、容量維持率を演算する。ステップＳ９にて、満充電容量演算部２９は、初期の満充電容量に、現在の容量維持率を乗ずることで、現在の満充電容量を演算する。   In step S7, the ΔSOC-i calculation unit 25 calculates the SOC change amount (ΔSOC-i) by an arithmetic expression represented by the ratio of the current integration value to the current full charge capacity of the battery 11. In step S8, the capacity maintenance ratio calculation unit 28 calculates a capacity maintenance ratio according to an arithmetic expression represented by the ratio of the SOC change (ΔSOC-v) to the SOC change (ΔSOC-i). In step S9, full charge capacity calculation unit 29 calculates the current full charge capacity by multiplying the initial full charge capacity by the current capacity retention rate.

上記のように、本実施形態では、バッテリの電流の絶対値が０アンペア近傍になる第１時点からバッテリの電流の絶対値が０アンペア近傍になる第２時点までの期間を積算期間として特定し、積算期間におけるバッテリの電流の積算値を演算し、バッテリの検出電圧に基づき第１時点における第１開放電圧及び第２時点における第２開放電圧を演算し、第１開放電圧と第２開放電圧との電圧差と推定条件を満たす積算値とに基づきバッテリの容量維持率を推定する。このとき、積算値が所定の下限値以上であり、かつ、前記積算期間における前記バッテリの電流の平均値が所定値以上であることを、推定条件として設定されている。これにより、センサの検出誤差に対して影響の小さい電流積算値を用いて、容量維持率を演算するため、容量維持率の推定精度を高めることができる。   As described above, in the present embodiment, a period from the first point in time when the absolute value of the battery current is near 0 amperes to the second point in time when the absolute value of the battery current is near 0 amperes is specified as the integration period. Calculating the integrated value of the battery current during the integration period, calculating the first open circuit voltage at the first time point and the second open circuit voltage at the second time point based on the detected voltage of the battery, the first open voltage and the second open voltage The capacity maintenance ratio of the battery is estimated based on the voltage difference between and the integrated value satisfying the estimation condition. At this time, it is set as the estimation condition that the integrated value is equal to or more than a predetermined lower limit value and the average value of the current of the battery in the integration period is equal to or more than a predetermined value. As a result, since the capacity maintenance rate is calculated using the current integration value that has a small influence on the detection error of the sensor, it is possible to improve the estimation accuracy of the capacity maintenance rate.

ここで、電流積算値と容量維持率の演算誤差との関係について、図８を用いて説明する。図８は、電流積算値と演算誤差との関係を示すグラフである。図８において、菱形は、電流積算値に対する演算誤差の測定値をプロットしたものである。容量維持率の演算は、図３に示す制御フローで実行した演算方式（以下、ΔＳＯＣ演算方式とも称す）を用いている。   Here, the relationship between the current integration value and the calculation error of the capacity retention rate will be described with reference to FIG. FIG. 8 is a graph showing the relationship between the current integration value and the calculation error. In FIG. 8, the rhombus is a plot of the measurement value of the calculation error with respect to the current integration value. The calculation of the capacity retention rate uses the calculation method (hereinafter also referred to as ΔSOC calculation method) executed in the control flow shown in FIG.

電流積算値は、上記の推定条件に限定せず、少なくともゼロより高くしつつ、広い範囲としている。また演算誤差は、ＳＯＣ演算方式を使って演算した演算値と、実際の容量維持率との差に相当する。そして、許容できる演算誤差の下限値をＣＬとし、上限値をＣＨとする。The current integrated value is not limited to the above-described estimation condition, and is in a wide range while at least higher than zero. The calculation error corresponds to the difference between the calculated value calculated using the SOC calculation method and the actual capacity retention rate. Then, the lower limit of the allowable calculation error and C L, the upper limit value C H.

図８に示すように、電流積算値がゼロに近い値で、演算誤差が最も大きくなる。そして、電流積算値の絶対値が大きくなるにつれて、演算誤差が小さくなる。さらに電流積算値の絶対値が大きくなると、所定の領域を境に、演算誤差が再び大きくなる。プロットされた測定値に対して、近似曲線を描くと、グラフａのようなグラフとなる。そして、近似曲線ａと演算誤差の上限値ＣＨとの交点で示される範囲Ａが、電流積算値に対した演算誤差が小さくなる範囲となる。範囲Ａは、近似曲線ａと演算誤差の下限値ＣＬとの交点で示される範囲とも同じ範囲となる。As shown in FIG. 8, the calculation error is the largest when the current integrated value is close to zero. Then, as the absolute value of the current integration value increases, the calculation error decreases. When the absolute value of the current integration value further increases, the calculation error increases again at a predetermined area. When an approximate curve is drawn on the plotted measured values, a graph such as graph a is obtained. Then, the range A indicated by the intersection of the approximate curve a and the upper limit value C H of the operation error, a range of calculation error becomes smaller that against the accumulated current value. The range A is the same as the range indicated by the intersection of the approximate curve a and the lower limit value C L of the operation error.

本実施形態では、範囲Ａに相当する電流積算値の上限値及び下限値を、推定条件における電流積算値の上限値及び下限値に設定している。図８に示すように、推定条件を満たす電流積算値は、範囲Ａ内に含まれることになるため、演算誤差は、範囲Ａ外の誤差と比較して小さくなる。これにより、推定条件を満たす電流積算値を演算対象にすることで、容量維持率の推定精度を高めることができる。   In the present embodiment, the upper limit value and the lower limit value of the current integration value corresponding to the range A are set as the upper limit value and the lower limit value of the current integration value under the estimation condition. As shown in FIG. 8, since the current integrated value satisfying the estimation condition is included in the range A, the calculation error is smaller than the error outside the range A. As a result, by making the current integration value satisfying the estimation condition the calculation target, it is possible to improve the estimation accuracy of the capacity retention rate.

また本実施形態では、ゼロ電流時点の間の期間を、容量維持率の演算対象の期間に設定している。これにより、開放電圧（無負荷電圧）の推定精度を高め、満充電容量の演算精度を向上させることができる。   Further, in the present embodiment, the period between zero current points is set as the period for which the capacity maintenance ratio is to be calculated. As a result, the estimation accuracy of the open circuit voltage (no-load voltage) can be improved, and the calculation accuracy of the full charge capacity can be improved.

ここで、図９を用いて、演算方式とＳＯＣ誤差との関係について説明する。ＳＯＣを演算する方式として、電流積算値及び開放電圧からＳＯＣを演算する方式が考えられる。すなわち、この方式は、開放電圧から求めたＳＯＣ（以下、ＳＯＣ-ｖ）と電流積算値から求めたＳＯＣ（以下、ＳＯＣ-ｉ）とを所定の比率で合算する（重み付け合成する）ことによってＳＯＣを演算する方式であり、以下ではブレンド方式とも言う。ブレンド方式のＳＯＣ算出方法において、電流値が比較的小さい場合にはＳＯＣ-ｖの比率が大きい比率に設定され、ＳＯＣ-ｉの比率が小さい比率に設定される。電流値が比較的大きい場合にはＳＯＣ-ｉの比率が大きい比率に設定され、ＳＯＣ-ｖの比率が小さい比率に設定される。そして、設定されたＳＯＣ-ｉの比率及び設定されたＳＯＣ-ｖの比率を合算することで、ＳＯＣが算出される。なお、このようなブレンド方式のＳＯＣ算出方法は例えば特開２０１３-２１７８９９号等に記載の通りよく知られた算出方法であり、以下では詳述しない。また、本実施形態においてはＳＯＣ算出方法をＳＯＣ-ｖとＳＯＣ-ｉとを所定の比率で合算するブレンド方式として記載するが、ＳＯＣ算出方法はブレンド方式に限らない。例えば電流値に応じてＳＯＣ-ｖとＳＯＣ-ｉとのいずれかをＳＯＣとして採用するＳＯＣ算出方法であってもよい。   Here, the relationship between the arithmetic method and the SOC error will be described with reference to FIG. As a method of calculating SOC, a method of calculating SOC from a current integrated value and an open circuit voltage can be considered. That is, in this method, the SOC is obtained by summing (weighting and combining) the SOC (hereinafter referred to as SOC-v) obtained from the open circuit voltage and the SOC (hereinafter referred to as SOC-i) obtained from the current integration value. In the following, it is also called a blend method. In the blend type SOC calculation method, when the current value is relatively small, the ratio of SOC-v is set to a large ratio, and the ratio of SOC-i is set to a small ratio. When the current value is relatively large, the ratio of SOC-i is set to a large ratio, and the ratio of SOC-v is set to a small ratio. Then, the SOC is calculated by summing the set SOC-i ratio and the set SOC-v ratio. Incidentally, such a blend type SOC calculation method is a well-known calculation method as described in, for example, Japanese Patent Application Laid-Open No. 2013-217899 etc., and will not be described in detail below. Further, in the present embodiment, although the SOC calculation method is described as a blend method in which SOC-v and SOC-i are added at a predetermined ratio, the SOC calculation method is not limited to the blend method. For example, an SOC calculation method may be employed in which one of SOC-v and SOC-i is adopted as the SOC according to the current value.

図９はブレンド方式でＳＯＣを演算したときのＳＯＣ誤差である。そして、時間ｔＡから時間ｔＢまでの期間は、電流が小さくなった期間であり、時間０から時間ｔＡまでの期間及び時間ｔＢ以降の期間は電流が大きくなった期間である。ゼロ電流時点は、時間ｔＡから時間ｔＢの期間内にあったとする。FIG. 9 shows the SOC error when the SOC is calculated by the blend method. Then, from time t A to time t B is the time period the current is decreased, the period and the time t B later in the period from time 0 to time t A is the period of time when the current is increased. The zero current point is assumed to be within the period from time t A to time t B.

ブレンド方式のＳＯＣ算出方法においては、時間０から時間ｔＡまでの期間及び時間ｔＢ以降の期間は電流値が大きいためＳＯＣ-ｉの合成比率が大きく、ＳＯＣ-ｖの合成比率が小さい。一方、時間ｔＡから時間ｔＢまでの期間はＳＯＣ-ｖの合成比率が大きく、ＳＯＣ-ｉの合成比率が小さい。合成比率は、ＳＯＣ-ｉの比率とＳＯＣ-ｖの比率とを合算した合算比率に対する割合に相当する。In the blend type SOC calculation method, since the current value is large in the period from time 0 to time t A and the period after time t B , the synthesis ratio of SOC-i is large and the synthesis ratio of SOC-v is small. On the other hand, in the period from time t A to time t B , the synthesis ratio of SOC-v is large, and the synthesis ratio of SOC-i is small. The combined ratio corresponds to a ratio to a combined ratio obtained by adding the ratio of SOC-i and the ratio of SOC-v.

時間０を始点として、電流積算値に基づくＳＯＣ-ｉの合成比率が高いため、電流センサ１２による誤差が時間の経過と共に積み上がる。時間ｔＡ以降も電流積算値に基づくＳＯＣ-ｉの合成比率が高いままであると、電流が低くなっても、誤差は積み上がり、電流誤差はさらに積み上がる。一方、電流値が小さい場合にはＳＯＣ-ｖの合成比率を大きくするブレンド方式であれば、ゼロ電流時点における電圧に基づいて開放電圧を演算し、この開放電圧を用いて算出したＳＯＣ-ｖの合成比率が大きくなるため、ゼロ電流時点における開放電圧に基づくＳＯＣの演算が、電流積算値に基づくＳＯＣ誤差を補正していることになる。すなわち、ブレンド方式では、電流積算値に基づくＳＯＣの推定誤差を、ゼロ電流地点時点における開放電圧に基づくＳＯＣの推定によって、補正を行っていることなる。その結果として、満充電容量の演算精度を向上させることができる。Since the composite ratio of SOC-i based on the current integrated value is high starting from time 0, the error due to the current sensor 12 is accumulated as time passes. If the combined ratio of SOC-i based on the current integration value remains high even after time t A , the error is accumulated even if the current is lowered, and the current error is further accumulated. On the other hand, in the case of a blend method in which the synthesis ratio of SOC-v is increased when the current value is small, the open circuit voltage is calculated based on the voltage at the zero current point, and the SOC of v calculated using this open circuit voltage Since the combining ratio becomes large, the calculation of the SOC based on the open circuit voltage at the zero current point corrects the SOC error based on the current integration value. That is, in the blending method, the estimation error of the SOC based on the current integrated value is corrected by the estimation of the SOC based on the open circuit voltage at the zero current point. As a result, the calculation accuracy of the full charge capacity can be improved.

また本実施形態では、積算値が所定の下限値以上から上限値以下までの範囲が推定条件として設定されている。これにより、センサの検出誤差に対して影響の小さい電流積算値を用いて、容量維持率を演算するため、容量維持率の推定精度を高めることができる。   Further, in the present embodiment, a range from the integrated value being at least the predetermined lower limit value to the upper limit value is set as the estimation condition. As a result, since the capacity maintenance rate is calculated using the current integration value that has a small influence on the detection error of the sensor, it is possible to improve the estimation accuracy of the capacity maintenance rate.

また、本実施形態の変形例として、推定条件判定部２４は、容量維持率の推定値に基づき、推定条件に含まれる電流積算値の下限値を設定してもよい。図１０は、バッテリ１１の電流変化（図１０（ａ）に示す変化）及び電圧変化（図１０（ｂ）に示す変化）の一例を示すグラフである。   In addition, as a modification of the present embodiment, the estimation condition determination unit 24 may set the lower limit value of the current integration value included in the estimation condition based on the estimated value of the capacity maintenance rate. FIG. 10 is a graph showing an example of the current change (change shown in FIG. 10A) and the voltage change (change shown in FIG. 10B) of the battery 11.

図１０に示す電流及び電圧変化は、バッテリが、ある充電状態（ＳＯＣＳ）から充電された際の変化であって、グラフａは初期状態（劣化前）の電流変化を示し、グラフｂは劣化後の電流変化を示す。また時間ｔｐは、初期状態のバッテリ１１において、時間ｔ０から積算された電流積算値が推定条件の下限値に達した時間を表している。The current and voltage changes shown in FIG. 10 are changes when the battery is charged from a certain state of charge (SOC S ), and graph a shows current change in the initial state (before deterioration) and graph b shows deterioration It shows the later current change. The time t p represents the time when the current integrated value integrated from the time t 0 reaches the lower limit value of the estimation condition in the battery 11 in the initial state.

バッテリ１１の管理を行う際には、バッテリ１１の保護を目的として、ＳＯＣの上限値（ＳＯＣＨ）が予め設定されている。バッテリコントローラ２０はバッテリ１１のＳＯＣが上限値（ＳＯＣＨ）より高くならないように、バッテリ１１を管理している。初期状態のバッテリ１１では、ＳＯＣＳから充電を開始した場合に、ＳＯＣがＳＯＣＨに達する前に、充電電流の積算値が推定条件の下限値に達する。そのため、時間ｔ０から時間ｔｐまでに積層された電流積算値を、容量維持率の推定制御に用いることができる。When managing the battery 11, for protection of the battery 11, the upper limit of the SOC (SOC H) is set in advance. The battery controller 20, as the SOC of the battery 11 is not higher than the upper limit value (SOC H), manages the battery 11. In the battery 11 in the initial state, when charging is started from the SOC S , the integrated value of the charging current reaches the lower limit value of the estimation condition before the SOC reaches the SOC H. Therefore, the current integrated value are stacked in from time t 0 to time t p, it can be used for estimation control of the capacity maintenance ratio.

一方、バッテリ１１が劣化した場合には、満充電容量が小さくなるため、充電電流を同じ値とした時、劣化後のＳＯＣの変化量（図１１（ｂ）のグラフの傾きに相当）は初期状態（劣化前）のＳＯＣの変化量よりも大きくなる。そして、充電電流の積算値が推定条件の下限値に達する前に、時間ｔｑの時点で、ＳＯＣが上限値（ＳＯＣＨ）に達し、充電電流は低くなる。そのため、容量維持率を推定する頻度が少なくなる。On the other hand, when the battery 11 is deteriorated, the full charge capacity is reduced. Therefore, when the charging current is set to the same value, the amount of change in SOC after deterioration (corresponding to the slope of the graph in FIG. It becomes larger than the amount of change of SOC in the state (before deterioration). Then, before the integrated value of the charging current reaches the lower limit of the estimated condition, at time t q, SOC reaches the upper limit value (SOC H), the charging current becomes lower. Therefore, the frequency of estimating the capacity maintenance rate is reduced.

図１１に示す特性は、図１０と同様に、バッテリが、ある電圧（ＶＳ）から充電された際の電流及び電圧変化の一例であって、グラフａは初期状態（劣化前）の特性を示し、グラフｂは劣化後の特性を示す。また時間ｔｐは、初期状態のバッテリ１１において、時間ｔ０から積算された電流積算値が推定条件の下限値に達した時間を表している。The characteristic shown in FIG. 11 is an example of current and voltage change when the battery is charged from a certain voltage (V S ) as in FIG. 10, and graph a shows the characteristic in the initial state (before deterioration). Graph b shows the characteristics after deterioration. The time t p represents the time when the current integrated value integrated from the time t 0 reaches the lower limit value of the estimation condition in the battery 11 in the initial state.

バッテリ１１の管理を行う際には、バッテリ１１の保護を目的として、電圧の上限値（ＶＨ）及び下限値（ＶＬ）が予め設定されている。バッテリコントローラ２０はバッテリ１１の電圧が上限値（ＶＨ）より高くならないように、バッテリ１１を管理している。初期状態のバッテリ１１では、ＶＳから充電を開始した場合に、バッテリ電圧がＶＨに達する前に、充電電流の積算値が推定条件の下限値に達する。そのため、時間ｔ０から時間ｔｐまでに積層された電流積算値を、容量維持率の推定制御に用いることができる。When managing the battery 11, the upper limit value (V H ) and the lower limit value (V L ) of the voltage are set in advance for the purpose of protecting the battery 11. The battery controller 20 manages the battery 11 so that the voltage of the battery 11 does not become higher than the upper limit value (V H ). In the battery 11 in the initial state, when charging is started from V S , the integrated value of the charging current reaches the lower limit value of the estimation condition before the battery voltage reaches V H. Therefore, the current integrated value are stacked in from time t 0 to time t p, it can be used for estimation control of the capacity maintenance ratio.

バッテリ１１が劣化した場合には、満充電容量が小さくなり、バッテリ１１の内部抵抗が大きくなる。バッテリ電圧（Ｖ）、開放電圧（Ｅ）、バッテリ電流（Ｉ）、及び内部抵抗（Ｒ）を含むバッテリ１１の関係式（Ｖ＝Ｅ＋ＩＲ）によると、内部抵抗が増加すると電流と内部抵抗によって発生する電圧（ＩＲ）の変化が増加し、満充電容量が小さくなると残充電電荷量の変化に伴う電圧変化、すなわち開放電圧（Ｅ）の変化が大きくなる。すなわち、バッテリ１１が劣化した場合に、バッテリ電圧は、バッテリ１１の劣化前と比較して、変化しやすくなり、上限値又は下限値に当たりやすくなる。図１１（ｂ）に示すように、充電電流の積算値が推定条件の下限値に達する前に、時間ｔｑの時点で、バッテリ電圧が上限値（ＶＨ）に達し、充電電流は低くなる。そのため、容量維持率を推定する頻度が少なくなる。When the battery 11 is degraded, the full charge capacity is reduced and the internal resistance of the battery 11 is increased. According to the relationship (V = E + IR) of the battery 11 including battery voltage (V), open circuit voltage (E), battery current (I), and internal resistance (R), when internal resistance increases, it is generated by current and internal resistance When the full charge capacity decreases, the voltage change accompanying the change of the remaining charge amount, that is, the change of the open circuit voltage (E) becomes large. That is, when the battery 11 is deteriorated, the battery voltage is easily changed as compared to before the deterioration of the battery 11, and is easily hit to the upper limit value or the lower limit value. As shown in FIG. 11B, the battery voltage reaches the upper limit value (V H ) at time t q before the integrated value of the charging current reaches the lower limit value of the estimation condition, and the charging current decreases. . Therefore, the frequency of estimating the capacity maintenance rate is reduced.

図１２に示す特性は、バッテリが、ある充電状態（ＳＯＣＳ）から放電された際の電流及びＳＯＣ変化の一例であって、グラフａは初期状態（劣化前）の電流変化を示し、グラフｂは劣化後のＳＯＣ変化を示す。また時間ｔｐは、初期状態のバッテリ１１において、時間ｔ０から積算された電流積算値が推定条件の下限値に達した時間を表している。The characteristic shown in FIG. 12 is an example of the change in current and SOC when the battery is discharged from a certain state of charge (SOC S ), and graph a shows the change in current in the initial state (before deterioration). Indicates the SOC change after deterioration. The time t p represents the time when the current integrated value integrated from the time t 0 reaches the lower limit value of the estimation condition in the battery 11 in the initial state.

バッテリ１１の管理を行う際には、バッテリ１１の保護を目的として、ＳＯＣの下限値（ＳＯＣＬ）が予め設定されている。バッテリコントローラ２０はバッテリ１１のＳＯＣが下限値（ＳＯＣＬ）より低くならないように、バッテリ１１を管理している。初期状態のバッテリ１１では、ＳＯＣＳから放電を開始した場合に、ＳＯＣがＳＯＣＬに達する前に、放電電流の積算値が推定条件の下限値に達する。そのため、時間ｔ０から時間ｔｐまでに積層された電流積算値を、容量維持率の推定制御に用いることができる。When managing the battery 11, the lower limit value (SOC L ) of the SOC is set in advance for the purpose of protecting the battery 11. The battery controller 20 manages the battery 11 so that the SOC of the battery 11 is not lower than the lower limit value (SOC L ). In the battery 11 in the initial state, when discharge is started from the SOC S , the integrated value of the discharge current reaches the lower limit value of the estimation condition before the SOC reaches the SOC L. Therefore, the current integrated value are stacked in from time t 0 to time t p, it can be used for estimation control of the capacity maintenance ratio.

一方、バッテリ１１が劣化した場合には、満充電容量が小さくなるため、放電電流を同じ値とした時、劣化後のＳＯＣの変化量（図１１（ｂ）のグラフの傾きに相当）は初期状態のＳＯＣの変化量よりも大きくなる。そして、放電電流の積算値が推定条件の下限値に達する前に、時間ｔｑの時点で、ＳＯＣが下限値（ＳＯＣＬ）に達し、放電電流はゼロになる。そのため、容量維持率を推定する頻度が少なくなる。On the other hand, when the battery 11 is deteriorated, the full charge capacity is reduced. Therefore, when the discharge current is set to the same value, the change amount of SOC after deterioration (corresponding to the slope of the graph of FIG. It becomes larger than the amount of change in SOC of the state. Then, before the integrated value of the discharge current reaches the lower limit value of the estimation condition, the SOC reaches the lower limit value (SOC L ) at time t q , and the discharge current becomes zero. Therefore, the frequency of estimating the capacity maintenance rate is reduced.

変形例に係る推定条件判定部２４は、容量維持率の推定値に基づき、推定条件の下限値を小さくする。具体的には、推定条件判定部２４は、容量維持率が小さくなるほど、推定条件の下限値を小さくする。または、推定条件判定部２４は、容量維持率が所定値より低い場合には、推定条件の下限値を小さくする。これにより、バッテリ１１が劣化した場合でも、容量維持率の演算頻度を確保できる。   The estimation condition determination unit 24 according to the modification reduces the lower limit value of the estimation condition based on the estimated value of the capacity maintenance rate. Specifically, the estimation condition determination unit 24 reduces the lower limit value of the estimation condition as the capacity retention rate decreases. Alternatively, when the capacity retention rate is lower than a predetermined value, the estimation condition determination unit 24 reduces the lower limit value of the estimation condition. As a result, even when the battery 11 is degraded, the calculation frequency of the capacity maintenance rate can be secured.

また、変形例に係る推定条件判定部２４は、容量維持率の推定値の代わり、バッテリ１１の内部抵抗又はバッテリ１１の使用期間に基づいて、推定条件の下限値を設定する。具体的には、推定条件判定部２４は、内部抵抗が高くなるほど、又は、使用期間が長くなるほど、推定条件の下限値を小さくする。または、推定条件判定部２４は、内部抵抗が所定値より高い場合に、又は、使用期間が所定時間より長い場合に、推定条件の下限値を所定値より小さくする。   Further, the estimation condition determination unit 24 according to the modification sets the lower limit value of the estimation condition based on the internal resistance of the battery 11 or the usage period of the battery 11 instead of the estimated value of the capacity maintenance rate. Specifically, the estimation condition determination unit 24 reduces the lower limit value of the estimation condition as the internal resistance increases or as the usage period increases. Alternatively, the estimation condition determination unit 24 makes the lower limit value of the estimation condition smaller than the predetermined value when the internal resistance is higher than the predetermined value or when the use period is longer than the predetermined time.

また本実施形態の変形例として、推定条件判定部２４は、電流積算値が下限値以上から上限値以下までの範囲内であること、及び、平均電流値が平均電流閾値未満であることに加えて、温度センサ１４の検出電圧が所定の温度閾値以上であることを、推定条件に加える。   Further, as a modification of the present embodiment, the estimation condition determination unit 24 adds that the current integrated value is within the range from the lower limit value to the upper limit value and that the average current value is less than the average current threshold. The fact that the detected voltage of the temperature sensor 14 is equal to or higher than a predetermined temperature threshold is added to the estimation condition.

図１３は、バッテリ１１の温度に対する内部抵抗の特性を示すグラフである。図１３に示すように、バッテリ１１の特性として、バッテリ１１の温度が所定値以上である場合にはバッテリ１１の内部抵抗は一定値で推移する。一方、バッテリ１１の温度が所定値未満である場合には、バッテリ１１の温度が低いほど、内部抵抗が大きくなる。また、低温領域における内部抵抗の上昇により、温度センサ１４の誤差が大きくなる。   FIG. 13 is a graph showing the characteristics of the internal resistance with respect to the temperature of the battery 11. As shown in FIG. 13, as the characteristic of the battery 11, when the temperature of the battery 11 is equal to or higher than a predetermined value, the internal resistance of the battery 11 changes at a constant value. On the other hand, when the temperature of the battery 11 is less than a predetermined value, the internal resistance increases as the temperature of the battery 11 decreases. In addition, an increase in internal resistance in the low temperature range causes an error in the temperature sensor 14 to be increased.

ＯＣＶ演算部２６が開放電圧を演算する際に、直線回帰演算方式を用いる場合には、演算式に内部抵抗を含むことになるため、低温領域では、開放電圧の誤差が大きくなる可能性がある。なお、直線回帰演算方式では、電流センサの検出値（Ｖ）、電圧センサの検出値（Ｉ）及びバッテリ１１の内部抵抗（Ｒ）を用いて、演算式（Ｖ＝Ｅ＋Ｉ×Ｒ）により開放電圧（Ｅ）を求める方式である。   When the OCV calculation unit 26 calculates the open circuit voltage, when the linear regression calculation method is used, since the calculation formula includes the internal resistance, the error of the open circuit voltage may be large in the low temperature region . In the linear regression operation method, the open voltage is obtained by an arithmetic expression (V = E + I × R) using the detection value (V) of the current sensor, the detection value (I) of the voltage sensor, and the internal resistance (R) of the battery 11. This is a method for obtaining (E).

そのため、変形例では、推定条件判定部２４は、温度センサ１４の検出電圧が所定の温度閾値以上であることを、推定条件に加える。これにより、低温領域における温度センサの誤差による影響を抑制しつつ、容量維持率の演算精度を高めることができる。   Therefore, in the modification, the estimation condition determination unit 24 adds that the detection voltage of the temperature sensor 14 is equal to or higher than a predetermined temperature threshold to the estimation condition. As a result, it is possible to enhance the calculation accuracy of the capacity retention rate while suppressing the influence of the error of the temperature sensor in the low temperature region.

また本実施形態の変形例として、推定条件判定部２４は、電流積算値が下限値以上から上限値以下までの範囲内であること、及び、平均電流値が平均電流閾値未満であることに加えて、電流センサ１２の検出電流が、所定時間、所定の電流閾値以上であることを、推定条件に加えてもよい。図６に示したように、電流積算期間のうち、低電流の期間が長く続くと、電流センサ１２の誤差が電流積算値に積み上がることで、容量維持率の演算精度が低くなる。そのため、変形例に係る推定条件判定部２４は、バッテリ１１の電流値の条件を加えることで、電流積算期間が低電流期間（図６に示す時間ｔ１以降の電流期間）を含む場合に、当該電流積算期間における電流積算値を、演算対象から除外している。これにより、容量維持率の推定精度を高めることができる。Further, as a modification of the present embodiment, the estimation condition determination unit 24 adds that the current integrated value is within the range from the lower limit value to the upper limit value and that the average current value is less than the average current threshold. The fact that the current detected by the current sensor 12 is equal to or greater than a predetermined current threshold may be added to the estimation condition. As shown in FIG. 6, when the low current period continues for a long time in the current integration period, the error of the current sensor 12 is accumulated on the current integration value, and the calculation accuracy of the capacity retention rate is lowered. Therefore, estimating the condition determining unit 24 according to the modified example, the addition of conditions of the current value of the battery 11, when the current integration period comprises a low-current period (current period time t 1 later shown in FIG. 6), The current integration value in the current integration period is excluded from the calculation target. Thereby, the estimation accuracy of the capacity maintenance rate can be enhanced.

なお、本実施形態により推定された容量維持率は、容量維持率演算部２８で演算された容量維持率、又は、満充電容量演算部２９で演算された満充電容量に相当する。   The capacity maintenance rate estimated according to the present embodiment corresponds to the capacity maintenance rate calculated by the capacity maintenance rate calculation unit 28 or the full charge capacity calculated by the full charge capacity calculation unit 29.

上記の電流センサ１２及び電圧センサ１３が本発明に係る検出部に相当し、推定条件判定部２４、ΔＳＯＣ−ｉ演算部２５、ΔＳＯＣ−ｖ演算部２７、及び容量維持率演算部２８、満充電容量演算部２９が本発明に係る容量維持率推定部に相当する。   The current sensor 12 and the voltage sensor 13 correspond to a detection unit according to the present invention, and the estimated condition determination unit 24, the ΔSOC-i calculation unit 25, the ΔSOC-v calculation unit 27, the capacity retention ratio calculation unit 28, and the full charge The capacity calculation unit 29 corresponds to a capacity maintenance rate estimation unit according to the present invention.

１…バッテリパック
１０…セル
１１…バッテリ
１２…電流センサ
１３…電圧センサ
１４…温度センサ
２０…バッテリコントローラ
２１…ゼロ電流時点特定部
２２…電流積算値演算部
２３…平均電流演算部
２４…推定条件判定部
２５…ΔＳＯＣ−ｉ演算部
２６…ＯＣＶ演算部
２７…ΔＳＯＣ−ｖ演算部
２８…容量維持率演算部
２９…満充電容量演算部DESCRIPTION OF SYMBOLS 1 battery pack 10 cell 11 battery 12 current sensor 13 voltage sensor 14 temperature sensor 20 battery controller 21 zero current point specification part 22 integrated current value calculation part 23 average current calculation part 24 estimation condition Determination unit 25 ... ΔSOC-i calculation unit 26 ... OCV calculation unit 27 ... ΔSOC-v calculation unit 28 ... capacity maintenance ratio calculation unit 29 ... full charge capacity calculation unit

Claims (8)

バッテリの容量維持率を推定する容量維持率推定装置であって、
前記バッテリの電流及び前記バッテリの電圧を検出する検出部と、
前記バッテリの電流の絶対値が０アンペア近傍になる第１時点から前記バッテリの電流の絶対値が０アンペア近傍になる第２時点までの期間を積算期間として特定し、前記検出部により検出された前記バッテリの検出電流に基づき、前記積算期間における前記バッテリの電流の積算値を演算する電流積算値演算部と、
前記検出部により検出された検出電圧に基づき前記第１時点における前記バッテリの第１開放電圧を演算し、前記検出部により検出された検出電圧に基づき前記第２時点における前記バッテリの第２開放電圧を演算する開放電圧演算部と、
前記第１開放電圧と前記第２開放電圧との電圧差と所定の条件を満たす前記積算値とに基づき前記バッテリの容量維持率を推定する容量維持率推定部とを備え、
前記所定の条件は、前記積算値が所定の下限値以上であり、かつ、前記積算期間における前記バッテリの電流の平均値が所定値以上である
容量維持率推定装置。A capacity maintenance rate estimation device for estimating a capacity maintenance rate of a battery, comprising:
A detection unit that detects the current of the battery and the voltage of the battery;
A period from a first point in time when the absolute value of the current of the battery is near 0 amperes to a second point in time when the absolute value of the current of the battery is near 0 amperes is specified as an integration period, and detected by the detection unit A current integration value calculation unit that calculates an integration value of the current of the battery in the integration period based on a detection current of the battery;
The first open circuit voltage of the battery at the first time is calculated based on the detected voltage detected by the detection unit, and the second open circuit voltage of the battery at the second time based on the detected voltage detected by the detection unit An open voltage calculation unit that calculates
A capacity maintenance ratio estimation unit configured to estimate a capacity maintenance ratio of the battery based on a voltage difference between the first open circuit voltage and the second open circuit voltage and the integrated value satisfying a predetermined condition;
The capacity maintenance ratio estimating apparatus according to claim 1, wherein the predetermined condition is that the integrated value is equal to or higher than a predetermined lower limit, and an average value of current of the battery in the integration period is equal to or higher than a predetermined value. 前記所定の条件は、前記積算値が前記所定の下限値以上から所定の上限値以下の範囲である
請求項１記載の容量維持率推定装置。The capacity maintenance ratio estimation apparatus according to claim 1, wherein the predetermined condition is a range in which the integrated value is equal to or more than the predetermined lower limit value and equal to or less than a predetermined upper limit value. 前記検出部は前記バッテリの温度を検出し、
前記所定の条件は、前記バッテリの温度が所定の温度閾値以上である
請求項１又は２記載の容量維持率推定装置。The detection unit detects the temperature of the battery,
The capacity maintenance ratio estimation apparatus according to claim 1, wherein the predetermined condition is that the temperature of the battery is equal to or higher than a predetermined temperature threshold. 前記所定の条件は、前記バッテリの検出電流の絶対値が、所定期間、所定の電流閾値以上である
請求項１〜３のいずれか一項に記載の容量維持率推定装置。The capacity maintenance ratio estimating apparatus according to any one of claims 1 to 3, wherein the predetermined condition is that an absolute value of a detection current of the battery is equal to or more than a predetermined current threshold for a predetermined period. 前記開放電圧演算部は、
前記第１時点から所定の分極期間の経過後の前記バッテリの検出電圧に基づき前記第１開放電圧を演算し、前記第２時点から所定の分極期間の経過後の前記バッテリの検出電圧に基づき前記第２開放電圧を演算する
請求項１〜４のいずれか一項に記載の容量維持率推定装置。The open voltage calculation unit
The first open circuit voltage is calculated based on the detected voltage of the battery after the lapse of a predetermined polarization period from the first time point, and the detected voltage of the battery after the lapse of the predetermined polarization period from the second time point The capacity | capacitance maintenance factor estimation apparatus as described in any one of Claims 1-4 which calculates 2nd open circuit voltage. 前記容量維持率推定部は、前記容量維持率の推定値に基づき、前記所定の下限値を設定する
請求項１〜５のいずれか一項に記載の容量維持率推定装置。The capacity maintenance rate estimation device according to any one of claims 1 to 5, wherein the capacity maintenance rate estimation unit sets the predetermined lower limit value based on the estimated value of the capacity maintenance rate. 前記容量維持率推定部は、前記バッテリの内部抵抗又は前記バッテリの使用期間に基づき、前記所定の下限値を設定する
請求項１〜５のいずれか一項に記載の容量維持率推定装置。The capacity maintenance rate estimating device according to any one of claims 1 to 5, wherein the capacity maintenance rate estimating unit sets the predetermined lower limit value based on an internal resistance of the battery or a use period of the battery. バッテリの容量維持率を推定する容量維持率推定方法であって、
センサを用いて、前記バッテリの電流及び前記バッテリの電圧を検出し、
前記バッテリの電流の絶対値が０アンペア近傍になる第１時点から前記バッテリの電流の絶対値が０アンペア近傍になる第２時点までの期間を積算期間として特定し、
前記センサにより検出された前記バッテリの検出電流に基づき、前記積算期間における前記バッテリの電流の積算値を演算し、
前記センサにより検出された検出電圧に基づき前記第１時点における前記バッテリの第１開放電圧を演算し、
前記センサにより検出された検出電圧に基づき前記第２時点における前記バッテリの第２開放電圧を演算し、
前記第１開放電圧と前記第２開放電圧との電圧差を演算し、
所定の条件を満たす前記積算値と前記電圧差とに基づき前記バッテリの容量維持率を推定し、
前記所定の条件は、前記積算値が所定の下限値以上であり、かつ、前記積算期間における前記バッテリの電流の平均値が所定値以上である
容量維持率推定方法。A capacity maintenance rate estimation method for estimating a capacity maintenance rate of a battery, comprising:
A sensor is used to detect the current of the battery and the voltage of the battery;
A period from a first point in time when the absolute value of the current of the battery is near 0 amperes to a second point in time when the absolute value of the current of the battery is near 0 amperes is specified as an integration period.
The integrated value of the current of the battery in the integration period is calculated based on the detected current of the battery detected by the sensor;
Calculating a first open circuit voltage of the battery at the first time based on a detected voltage detected by the sensor;
Calculating a second open circuit voltage of the battery at the second time based on a detected voltage detected by the sensor;
Calculating a voltage difference between the first open circuit voltage and the second open circuit voltage;
Estimating the capacity retention rate of the battery based on the integrated value and the voltage difference that satisfy a predetermined condition;
The predetermined condition is that the integrated value is equal to or higher than a predetermined lower limit, and an average value of the current of the battery in the integration period is equal to or higher than a predetermined value.
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